Ruth is missing from the first part of book one, and Stan says that she is away visiting a relative. But she is later revealed to be Goldilocks, the pet chicken living in the house.
Kendra and Seth were responsible for taking care of Goldilocks while visiting Fablehaven for the first time. She was given kernels from a white plastic bucket and a tiny bowl of milk. She would lay an egg or two each day. She was in the children's room on Midsummer's Eve, and got attacked by some monsters.
Ruth Sorenson later admitted that she could not think straight while in bird form, and it took all of her concentration and effort to spell out letters with kernels, or even to communicate with her grandchildren and husband.
Ruth was turned into a chicken by the jinn in the dungeon below the house when he asked her a question she was unable to answer. She had known the danger of consulting a jinn, but opted to do it anyway, since the need was so great.
When Kendra and Seth discovered the chicken was their grandmother, they sought help from a witch named Muriel Taggert to transform her back to her original form, as their grandmother wanted. However, she did not know that the knot that Seth and Kendra blew on so Muriel could undo the spell was the last one and thus would set the witch free. Ruth led the assault on Muriel at the Forgotten Chapel, in hopes of saving Stan and Lena and preventing the release of the demon Bahumat. She fails and is captured, leaving Kendra alone to save them all.
Rise of the Evening Star
Grip of the Shadow Plague
Secrets of the Dragon Sanctuary
Keys to the Demon Prison